1. Field of the Invention
This invention relates to optical fiber connectors and particularly to a novel adjustable connector assembly for precisely aligning fiber ends.
2. Description of the Prior Art
In order to reduce light losses between butt-coupled optical fibers, the fiber ends must be precisely aligned exially and angularly with substantially no separation between the ends. One previous device for this purpose utilizes a baseplate with V-shaped grooves to hold the fibers, as shown in U.S. Pat. No. 3,768,146, issued Oct. 30, 1973. A metallic sleeve is crimped over the adjacent ends by a compression plate to secure and align the fibers within the groove. Another known device, as shown in U.S. Pat. No. 3,734,594, issued May 22, 1973, utilized a deformable annular core having pressure plates at the ends. The fiber ends are inserted into the core and a force on the plates deforms the core to align and secure the fibers. These prior art devices, however, did not readily provide sufficient accuracy for joining and aligning small diameter cores of optical fibers. An axial displacement of 5 microns, for example, can cause a loss of 1 dB for a 25 micron core fiber. Available displacement tolerances of about .+-.50 microns in conventional devices is therefore highly inadequate. A satisfactory device would require a tolerance of about .+-.2 microns, which would be very difficult and costly to achieve with known techniques.
The use of spacer fibers and a containing member to support a central optical fiber is also known, as shown in U.S. Pat. No. 3,535,017 issued Oct. 20, 1970. This, however, was for the purpose of providing particular transmission mode characteristics obtained by an asymetrical relationship of the elements. The arrangement did not provide coupling and precision alignment of adjacent fiber ends in an adjustable assembly.